Electronic equipment, especially cockpit avionics, are conventionally designed to operate according to parametric values established for a particular installation. By relying on parametric values that are associated with variations in installations (e.g., on different aircraft), the cost of design and qualification of avionics can be spread across many different installations and maintenance costs for a population of avionics may be reduced. In a typical installation and configuration, tables of alternative parametric values are stored in memory of a processor of the avionics; and, some external indication is ascertained for the selection of values particularly suitable for the current installation.
One technique is to choose a connector that is part of the permanent installation of the avionics (e.g., a connection already required for power, input, or output signals), reserve contacts in the connector for short circuits, define a code for the shorts, opens, and/or resistance between reserved contacts of that connector, and associate the code with a table of parametric values. In operation, the processor reads interface circuits that provide the code, uses the code as an index into the table, reads the parametric values from the table, and establishes, in accordance with the parameters, any operational criteria, such as, power conditioning, circuit functions, initial conditions, modes of operation, use of resources, identifications, limit conditions, and branch conditions. Giving effect to various parametric values may require switching circuitry for routing signals in alternate ways.
Avionics may be designed to permit the in situ installation of new software for use by the avionics. In a conventional arrangement, the avionics may have an interface connector (e.g., on a front or rear panel) for data communication signals used to accept the new software when on the ground or otherwise not in service. In situ installation of software avoids the expense of removing the avionics from some or all of its permanent installation (e.g., releasing mechanical restraints, extending circuit assemblies out of the position used in flight, disconnecting cables). Unfortunately, in situ installation of software is expensive in that it requires access to skilled personnel and equipment capable of providing the digital communication signals for transferring the software from such equipment to the avionics.
Without new methods for configuring avionics, the installation and maintenance of avionics will continue to be limited